Cast
Henry Victor
Baron Ernst von Steuben (U-boat commander)
William Collier Sr.
Mugs O'Flaherty (uncredited)
Ferdinand Schumann-Heink
Adolph Brucker (uncredited)
Warren Hymer
'Lug' Kaufman
John Loder
Franz Shiller
Hans Fuerberg
Fritz Kampf (Second Officer of U-172) (uncredited)
Maurice Murphy
Merkel (uncredited)
Walter McGrail
Chief Joe Cobb
Harry Tenbrook
Winkler (uncredited)
Mona Maris
Fraulein Lolita
Steve Pendleton
Ens. Richard 'Dick' Cabot (as Gaylord Pendleton)
Edward Peil Jr.
Naval Reservist (uncredited)
George Harris
Naval Reservist/Swimmer and Diver (uncredited)
Nat Pendleton
'Butch' Wagner (uncredited)
Jack Murphy
Naval Reservist (uncredited)
Joseph Depew
Naval Reservist (uncredited)
Harry Strang
Gunner and drill sergeant (uncredited)
George O'Brien
Cmdr. Robert 'Bob' Kingsley
Marion Lessing
Anna Marie Von Steuben
Walter C. Kelly
Chief Mike 'Guns' Costello
Larry Kent
Lt. 'Mac' McGregor
Francis Ford
Eric - Captain of Trawler (uncredited)